Tunable lasers have been of interest for some time. Applications range from broadband sensors to sources for fiber optic communications networks. In a fiber optic communications network the amount of information carried on a single optical fiber may be increased by multiplexing different optical signals on different wavelengths using wavelength division multiplexing (WDM). In a WDM-PON (passive optical network), for example, a single trunk fiber carries optical signals at multiple channel wavelengths to and from an optical branching point and the branching point provides a simple routing function by directing signals of different wavelengths to and from individual subscribers. At each subscriber location, an optical networking terminal is assigned one or more of the channel wavelengths for sending and/or receiving optical signals. Obviously, a larger tuning range of a tunable laser corresponds to a larger number of possible channel wavelengths and, thus, to a larger amount of information that may be transmitted over a single optical fiber. There is, therefore, a need for widely tunable lasers, i.e. lasers having a large wavelength tuning range.